title: Enhanced bone regeneration of cortical segmental bone defects using porous titanium scaffolds incorporated with colloidal gelatin gels for time- and dose-controlled delivery of dual growth factors.
abstract: Porous titanium scaffolds are a promising class of biomaterials for grafting large bone defects, because titanium provides sufficient mechanical support, whereas its porous structure allows bone ingrowth resulting in good osseointegration. To reinforce porous titanium scaffolds with biological cues that enhance and continue bone regeneration, scaffolds can be incorporated with bioactive gels for time- and dose-controlled delivery of multiple growth factors (GFs). In this study, critical femoral bone defects in rats were grafted with porous titanium scaffolds incorporated with nanostructured colloidal gelatin gels. Gels were loaded with bone morphogenetic protein-2 (BMP-2, 3 μg), fibroblast growth factor-2 (FGF-2, 0.6 μg), BMP-2, and FGF-2 (BMP-2/FGF-2, ratio 5:1) or were left unloaded. GF delivery was controlled by fine tuning the crosslinking density of oppositely charged nanospheres. Grafted femurs were evaluated using in vivo and ex vivo micro-CT, histology, and three-point bending tests. All porous titanium scaffolds containing GF-loaded gels accelerated and enhanced bone regeneration: BMP-2 gels gave an early increase (0-4 weeks), and FGF-2 gels gave a late increase (8-12 weeks). Interestingly, stimulatory effects of 0.6 μg FGF-2 were similar to a fivefold higher dose of BMP-2 (3 μg). BMP-2/FGF-2 gels gave more bone outside the porous titanium scaffolds than gels with only BMP-2 or FGF-2, resulted in bridging of most defects and showed superior bone-implant integrity in three-point bending tests. In conclusion, incorporation of nanostructured colloidal gelatin gels capable of time- and dose-controlled delivery of BMP-2 and FGF-2 in porous titanium scaffolds is a promising strategy to enhance and continue bone regeneration of large bone defects.
authors.affiliation: 1 Orthopaedic Research Laboratory, Department of Orthopaedics, Erasmus University Rotterdam Medical Centre , Rotterdam, The Netherlands .
authors.forename: Johan
authors.initials: J
authors.lastname: van der Stok
authors.forename: Huanan
authors.initials: H
authors.lastname: Wang
authors.forename: Saber
authors.initials: S
authors.lastname: Amin Yavari
authors.forename: Michiel
authors.initials: M
authors.lastname: Siebelt
authors.forename: Marjan
authors.initials: M
authors.lastname: Sandker
authors.forename: Jan H
authors.initials: JH
authors.lastname: Waarsing
authors.forename: Jan A N
authors.initials: JA
authors.lastname: Verhaar
authors.forename: Holger
authors.initials: H
authors.lastname: Jahr
authors.forename: Amir A
authors.initials: AA
authors.lastname: Zadpoor
authors.forename: Sander C G
authors.initials: SC
authors.lastname: Leeuwenburgh
authors.forename: Harrie
authors.initials: H
authors.lastname: Weinans
mesh_terms: D000818:Animals; D055396:Bone Morphogenetic Protein 2 / Q000737:chemistry* / Q000494:pharmacology; D001861:Bone Regeneration; D016503:Drug Delivery Systems; D016222:Fibroblast Growth Factor 2 / Q000737:chemistry* / Q000494:pharmacology; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate / Q000737:chemistry / Q000494:pharmacology; D008297:Male; D049329:Nanostructures / Q000737:chemistry*; D051381:Rats; D017208:Rats, Wistar; D054457:Tissue Scaffolds; D014025:Titanium / Q000737:chemistry* / Q000494:pharmacology
chemical_list: C525720:Bmp2 protein, rat; D055396:Bone Morphogenetic Protein 2; D016222:Fibroblast Growth Factor 2; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate; D014025:Titanium